Agricultural harvesters, such as agricultural combines, travel through fields of agricultural crops harvesting the crop with a harvesting head. The harvesting head cuts the crops from the ground, carries the cut crop material to a central region of the harvesting head with conveyors, and sends the cut crop material rearward through a hole in the frame of the harvesting head. The agricultural combine receives the cut crop material in a feederhouse. Then it threshes, separates, and cleans the cut crop material. The crop residue (material other than grain or “MOG”) is either deposited in the field as a windrow, or is broadcast either side of the agricultural combine itself.
All of these operations require the smooth flow of cut crop material. In order to provide the smooth flow, the speed of conveyors, the spacing of various machine components, even the speed of the agricultural combine through the field must be controlled and.
One problem relates to draper harvesting heads. Draper heads have a frame that extends laterally, perpendicular to the direction of travel of the combine over the ground. To the leading edge of the draper head a reciprocating knife is fixed that severs the crop plants close to their roots. The crop plants fall backward onto endless belt conveyors. Two of these endless belt conveyors are disposed on either side of the draper head frame and convey the crop material inward toward a central region of the draper head. Another endless belt conveyor is located between both the side conveyors at the middle of the paper head. This center conveyor receives the cut crop material from both the side conveyors and drags the cut crop material rearward, through a hole in the frame of the draper head, where it is presented to the agricultural combine for further processing.
The thick mat of cut crop material supported on the two side conveyors does not travel at the same speed as the belt that carries it. There typically is a difference between the speed of the mats of cut crop material and the speed of the endless belts of the side conveyors that support and convey the mats.
If the speed of the endless belts of the side conveyors is too high there will be a large difference in speed between the mats and the endless belts that carry them (this is called “slippage” herein). The endless belts will batter the mat of cut crop material due to the high slippage, causing grain to fall out of the mat and onto the ground.
If the speed of the endless belts is too low, the slippage may be reduced to zero and the mat of cut crop material will become too thick. It may jam the draper head. Thus, operating the two side conveyors too fast poses a problem, and operating them too slow also poses a problem. Some slippage is good. Too much slippage is bad.
In order to control the slippage, a system must be able to measure the slippage. To measure the slippage, the system must be able to measure the difference in relative velocity of (1) the crop mat carried on top of the belt, and (2) the endless belt itself. In order to determine the slippage between the crop mat and the endless belt, both the speed of the crop mat and the speed of the endless belt which carries it should be determined and compared.
There is general prior art disclosing cameras to detect characteristics of crop plants (either crop plants standing in the field, cut crop on a harvesting head or cut crop inside the combine) and using those characteristics to control the mechanisms of the agricultural harvesting head or the combine.
U.S. Pat. No. 9,320,197 B2, for example, discloses a camera system for imaging unharvested crop standing in the field in front of harvesting head and using those images to control the speed of a conveyor carrying cut crop.
DE 102016202628 A1, for example, discloses using a camera located above the front of an auger platform to monitor the crop flow within the auger platform and (among other things) to change the rotational speed of the transverse conveyor screw. An auger platform is a harvesting head that uses an elongate helical auger (the “transverse conveyor screw”) instead of conveyor belts to carry the crop inwardly toward the central region of the harvesting head.
U.S. Pat. No. 6,119,442 A, for example, discloses using a machine vision apparatus to generate images of crop material being processed by the combine, generating an image signal of the crop material, transmitting the image signal to a DPU, comparing the image signal to a set point within the DPU, and generating an output signal corresponding to the difference between the setpoint and the image signal, and transmitting the output signal to an actuator configured to change a combine setting.
US 20160366821 A1, for example, discloses an imaging system including cameras mounted on a feederhouse that image crop material between the cutting portion of an agricultural harvesting head and the feederhouse of the agricultural combine itself. A controller determines the cross-sectional area of the cut crop material and adjusts one or more machine parameters autonomously.
None of these references disclose the problem of (or benefit for) regulating cut crop slippage on the side draper belts of a draper header. None of them disclose determining cut crop slippage.
What is needed is a method for controlling the amount of slippage between a cut crop mat and the endless belts that carry the cut crop mat to a central region of the draper head.
It is an object of this invention to provide such a method.